Would someone mind looking over my system and comment on any errors before I power up?

[Jeff From NJ]

I built a homebrew system around a Chinese split phase solar inverter and would appreciate someone taking a look and checking to see if I have any errors prior to powering it up. I know there are several ways to do this, but my goal has been to add a generator option into the mix and that sort of led me to the setup I am currently building.

The design of the system is to have the inverter connect to the 6 panels (for now), the grid, through the 30 amp manual transfer switch which comes out of a 60Amp breaker on the main board, and four LiFePO4 batteries (wired 24v 100Ah). Should the grid go down, and there's no sun, and I have no battery power left, I have a large manual A/B switch that switches the house from the inverter to a generator via the 30 Amp manual transfer switch which is connected to the house breaker box and has all the "important" circuits powered through it via a 60 Amp breaker in the main house breaker panel.

I've included the specs and several photos of the almost completed system showing the wiring and components.

Here are all the specs:
2S3P panels - six (260W, 30.6V, 8.5A)
four 12V 100MAh LiFePO4 batteries (wired together for 24v 100Ah)
SNAD 4KW 24VDC solar inverter with charger Pure Sine Wave ,split phases Output: 120V 240AC 60Hz
Rotary Changeover Switch - 660V 125A 3 Position 3 Phase - connecting grid and generator to inverter via Conn. Elect. manual transfer switch
On/Off Switch for panels - 12-48V Battery Cut Switch - 275 A continuous at DC 12V, 455 A intermittent at DC 12V, 1250 A momentary at DC 12V
Bus Bar - 600 amp 12 stud black/red - Not sure if I should get something like this
Battery Switch - 600A On/Off - For batteries
4 AWG for batteries and wiring between components
10 AWG wire between solar panels and on/off switch
Class T with 200 amp, 250AC/DC250V Fuse Block - after 600amp switch connected to batteries (or bus bar) and before inverter
Connecticut Electric EGS107501G2KIT 30 Amp Manual Transfer Switch Kit - to connect generator and inverter to important circuits

I am concerned about the entire setup, and afraid things are going to go up in smoke (including me when I switch on the breaker or the panels). I believe I am going quite a bit outside the norm, especially for a first attempt and would love to hear guidance from those that are more knowledgeable. I am also currently questioning if I should wire the four batteries together via 4AWG wire to get 24v 100Ah, or to connect them via two buss bars and then take the negative to the inverter and the positive bus bar to the 600Amp switch and then the T-fuse and then over to the the inverter for purposes of even recharging and discharging of batteries - it seems wiring the batteries together with 4Awg will create a charging/discharging/balancing issue. I saw a pair of 600Amp rack mounted bus bars for $80 that seems to fit the bill, but before walking down that path, and the expense for wire and the bars, wanted thoughts.

So, I was hoping someone would look over the setup prior to powering up to see if I am missing something or if I made any errors, and if it's not too much, letting me know if using two bus bars from the battery bank will achieve my goal of better charge/discharge or if I should just wire the batteries together for 24V 100Ah and forget the bus bars.

Really (truly) appreciate your time.
Thanks
Jeff

 

[Supervstech]

4awg is only good for 70A, I would wire the pair together with 1/0 cable, or 200A rated busbar... 4000W at 24V is 166ish amps, so if there is a surge capacity to the inverter it is capable of pulling well over that.

 

[Jeff From NJ]

4awg is only good for 70A, I would wire the pair together with 1/0 cable, or 200A rated busbar... 4000W at 24V is 166ish amps, so if there is a surge capacity to the inverter it is capable of pulling well over that.

I'm sorry for being dense, but are you saying is OK to use 4Awg to run each battery to a 200A bus bar and then from the bus bar, use 1/0 cable to the 600Amp switch and then 1/0 to the Class T fuse and then 1/0 to the inverter? Also, wouldn't the 600A bus bar I showed be beefier than a 200A busbar and be usable, or are you saying no need to spend for a 600A bus bar and just get a 200A less expensive one?

Thanks

 

[Supervstech]

I'm sorry for being dense, but are you saying is OK to use 4Awg to run each battery to a 200A bus bar and then from the bus bar, use 1/0 cable to the 600Amp switch and then 1/0 to the Class T fuse and then 1/0 to the inverter? Also, wouldn't the 600A bus bar I showed be beefier than a 200A busbar and be usable, or are you saying no need to spend for a 600A bus bar and just get a 200A less expensive one?

Thanks

Nope, I'm saying that 4ga is too small for the load the inverter is capable of.
1/0 is what I would recommend.

 

[Supervstech]

Yes, the 600A busbar is fine, but between the 12V batteries, and between each pair of batteries to the bussbar should be 1/0
2/0-4/0 should go to the inverter.

 

[Supervstech]

Will 4ga WORK? Sure, but it will limit what the inverter can do.
And if the inverter is struggling to get watts, it will heat up the wire quickly.

 

[Jeff From NJ]

Will 4ga WORK? Sure, but it will limit what the inverter can do.
And if the inverter is struggling to get watts, it will heat up the wire quickly.

This is the current battery layout, along with your suggestion to run 1/0 between the batteries and the Bar, and then 4Awg from the bar to the inverter. I could use 1/0 if you think it will help from the bar to the inverter, I'd have to buy more wire. Is this what you were suggesting, and if so, where would you place the two bus bars in this diagram?

Thanks

 

[Supervstech]

View attachment 167053
This is the current battery layout, along with your suggestion to run 1/0 between the batteries and the Bar, and then 4Awg from the bar to the inverter. I could use 1/0 if you think it will help from the bar to the inverter, I'd have to buy more wire. Is this what you were suggesting, and if so, where would you place the two bus bars in this diagram?

Thanks

Not 4awg, 4/0 Awg needs to go to inverter.

 

[Pappion]

2 lifepo4 in series is not optimal. Battle Born will sell matched sets for that. Better to buy ready made 24v lifepo4 batteries.

2S3P panels - six (260W, 30.6V, 8.5A). : 3 or more in parallel should have a fuse for each string. Issue is with one string shorted the others will dump to much current and exceed the wires rating. MC4 fuse holders make this easy.

10awg seems a bit light for 3 parallel strings (3x8.5=25.5A). They have ready made 8awg solar wires. Weather coating, MC4 attached.
Blue Sea wire and fuse charts

On/Off Switch for panels - 12-48V Battery Cut Switch : what is it's rating at 60VDC?
There are a lot of solar disconnect switches to chose from and some are circuit breakers too.
Solar panel switches.

 

[Jeff From NJ]

2 lifepo4 in series is not optimal. Battle Born will sell matched sets for that. Better to buy ready made 24v lifepo4 batteries.

2S3P panels - six (260W, 30.6V, 8.5A). : 3 or more in parallel should have a fuse for each string. Issue is with one string shorted the others will dump to much current and exceed the wires rating. MC4 fuse holders make this easy.

10awg seems a bit light for 3 parallel strings (3x8.5=25.5A). They have ready made 8awg solar wires. Weather coating, MC4 attached.
Blue Sea wire and fuse charts

On/Off Switch for panels - 12-48V Battery Cut Switch : what is it's rating at 60VDC?
There are a lot of solar disconnect switches to chose from and some are circuit breakers too.
Solar panel switches.

I already have four 12v 100Ah batteries, while I agree it would have been better to have two 24v 100Ah, at this point, I am not going to throw out what I have until I see in my system I have a problem, I'm almost $1000 into batteries.

I can fuse the two strings of panels, I read that my configuration didn't require it until I added a few more panels, but point taken.

On/Off Switch for panels - https://www.amazon.com/gp/product/B07413JWLD/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
There is no mention of how it would work at 60VDC

 

[Jeff From NJ]

Not 4awg, 4/0 Awg needs to go to inverter.

Seems like I need to buy a bunch of new wire :-(
Thanks for the suggestion

 

[Jeff From NJ]

For placement of the bus bars, someone on this board drew out this sketch looking for confirmation. Is this how I should set up my four 12V 100Ah batteries to get 24V 100Ah?